1. Field of the Invention
The present invention relates to surface acoustic wave filters (hereinafter, SAW filters) and duplexers using the SAW filters.
2. Background Art
In conventional SAW filters, signal wiring is made thicker than IDT electrodes. The thickness of the signal wiring, however, has not been explicitly specified because at some thickness, there is an increase in the propagation loss of signals passing through the signal wiring. For example, Japanese Patent Unexamined Publication No. H7-212175 has disclosed a specific thickness of the signal wiring, but the thickness cannot minimize the propagation loss of signals passing through the signal wiring.